Train control system



Jan. 3, 1933.

TRAIN CONTROL SYSTEM Original Filed Nov. 10 1926 2 Sheets-Shem l =5 m X R J N E & rs i 5% J I n g N fix I anvewtoz 233% WWW 2 m Jan- 3, 933 A. e. WILLIAMSON 1,893,315

TRAIN CONTROL SYSTEM Original Filed Nov. 10, 1926 2 Sheets-Sheet 2 LU I TEDQSTAT Patented Jan. 3, 1933 E's F-IC nnna G. wnmaMso-n, or cannncrn, PENNSYLVANIA, ASSIGNOR TO run UNION swrron" & SIGNAL COMPANY, or

Original application'filedffiovember 10, 1926, Serial v1N0. 147,403. -ZDivided.and this application ,filed November 14, man.

i The present invention relates to train control systems, the train or traffic controlling meansbeing of ,anysuitabler character such assignals or retarding or stopping devices or both, andhas for its. main object and feature the coordination of trackway and traincarriedequipmentin a simple and effective manner. g y This application is adivision of applican01; Ser. No. 147,403, filed November 10, 1926. j q a In the accompanying drawings the invention is disclosed,by way of illustration but not oflimitation, in several concrete and preferred forms of which:

Fig. 1 is a diagrammatic view of a trackway equipment capable of being used in connection with the invention;

"Fig. 2 is a diagrammatic viewofone form of train-carried equipment by means of which the invention may be practiced, when associated withsuitable trackway equipment of acharacter'such as shown by way. of example in Fig. 1; i

Fig. 8 is a diagrammaticviewof another forn ,oftrackway equipment capable of being usediin the practice of the invention; 2 Fig; 4 is. a diagrammatic View of a modified form of train-carriedequipment, more particularly intended to be used in connection with the trackwayumeans shown in Fig. 3; and-p.

V Fig. 5 is a graph showing one, of the operating characteristics of an electron tube or electron discharge deviceof the magnetron -type..- v I v i 7 3 R ferring to Fig. 2, 55' indicates a conductor extending along the line of way suit ably energized, under certain traflic conditions, to ,createa magnetic field or lines of ma-gneticiorcelabout said conductor. The lines of magnetic force are indicated by the 'circles'surrounding the conductor. Carried by thertrain, incloseproximity to'the conductor butisepa-rated therefrom by an air gap, is an electrontube or an electron discharge device, here of the vmagnetron type and indicated by MG, It will be noted that the. magnetron is so arrangedfthat. its. longitudinal. axis is; substantially parallel to the SWISSVALE, PENNSYLVANIA, .A' CORPORATION OF TRAIN CONTROL SYSTEM Serial No. 495,722;

lines of magnetic force, audit will therefore be apprehended that it is located within the zone of influence of the magnetic field of the conductor and is directly susceptible and responsive tothe lines of magnetic force about said conductor. The magnetron is here shown as being included ina charged traincarriedcircuit which may be traced as follows: from battery 182, wire 183, coil of translating device or relay 24, wire 184, plate 185, fi1ament17 5, wires 17 8 and 186 back to batteryl'82i Relay 24 is a traflic controlling relay and, in the present instance, controls a circuit as follows: from battery 182, wire 18 3, neutral armature 28, polarized armature 30, brake valve 33, back to battery 182. -Suit-' ablev means are provided to heat the filament of the magnetron tube, said means. here taking thevformof a circuit as follows: battery 17 6, wire17 7, filament; 17 5 and wire 178 back to battery 176. Relay .24 is intendedrto be merely representative ofthe general group of relay, means illustrated in detailand in many forms in application -Ser. No; 147,403 previously referred to. Sufiice it 'to' say here that 24 isbiased to assume a clear condition when current of an intermediate value. is flowing in the charged, circuit in which it, as

well as the plate and filament of the ma g- I netron tube, is included, and to assume a restricted condition when the value of the current flowing in said circuit is either increased .or decreased with respectto said intermediate value: Specifically, relay 24 is a direct-currentlpolarized relay havingv a neutral armature 28 and a polarized armature 30, the arrangement being such that, if current of full value (here represented by 1.0.0) is flowing in the coils of relay 24, neutral armature 28 will be in its-upper position and'polarized armature 30 will occupy the left-hand position (as viewed in Fig. 2) ,that, if current of an intermediate value (here represented'by 0.20) is flowing through the coils of. relay 24, neutral armature 28 will still occupy the upper position but polarized armature'30 will occupy the right-hand position indicatediin Fig. 2; and that, if current below the value of 0.20 is flowing,or1if there should be a complete ab sence of current, in the coils of relay 24, then 100,

neutral armature 28 will drop and polarized armature 30 will seek the left-hand position, as viewed in Fig. 2. Thus polarized ar1na ture 30.0ccupies only the right-hand position current from battery 182 will flow in the,

charged circuit and in the coils of relay 24, said currentpassing from the plate to the filament of the magnetron tube which acts as a detector. In these circumstances, armature 28 will be in the up position, but polarized armature 30 will be in the left hand position and therefore the circuit through brake valve 33 will be ruptured. If, on the other hand, a magneticfield of suflicient strength is created about conductor 55, thecurrent flow from plate 185 to filament 175 will be choked fdown. Consequently, current of the intermediate value will flow in the charged circuit and through coils of relay 24. Therefore,-armature 28 will remain in the up position and armature 30 will seekits righthand position, thus maintaining the circuit through 33 closed. If there be a broken wire or a leakagein the charged circuit of such amplitude as to reduce the current fiowbelow the prescribed intermediate value, then armature 28 will drop and armature 30 will seek the left-hand position thereby rupturing the circuit through 33. It will now be understood that presence of a suificiently strong magnetic field about conductor represents one .trattic condition, in this instance clear trafiicconditions, and that absence of said suificiently strong magnetic field represents another, in this instancea restricted traific condition.

If conductor 55 is a conductor coextensive with the right of way it will be understood that the train-carried equipment will be continuously responsive to and controlled by the magnetic condition of said conductor, and that the latter may be arranged in blocks insuch manner that the traific conditions of one block controls the magnetic condition of another block, I a

- In this instance, conductor 55 is one of the trailic rails, and in such case the other traific rail 56 may likewise have a. magnetic field I created thereabout. In these conditions, a second magnetron tube MG may be used and th s will be placed within the zone of influence of rail 56. Filament 179 of MG is heated by connecting wires'180 and 181 to wires 177 and 178, and the plate-filament circuit of MG will beplaced in parallel with the charged circuit by extending wire 187 from plate 188 to wire 184.

Assuming nowthat'both'traflic rails are being used to control train-carried magacross the rails by suitable leads, and at the outgoing end of each block in a track battery 158 which is connected across the rails by .leads 150 and 156. The function of this battery is merely to energize a track relay like 148it is not suificiently powerful to create, about the conductors, magnetic fields of such value that themagnetron tubes effectively respond thereto. The train control current is here supplied from generator 51, in this instance of the alternating current type, by way of line wires 52 and 53 to aitrack transformer associated with each'block. Taking block B as an example, it willbe seen that the primary of track transformer 101 is connected by wires 143 and 144 to line wires 52 and 53. Secondary 145 of the track transformer is connected to rail 56 by wire 146, armature 147 (of the track relay of the block in advance) contact 149 and wire150, and s connected to rail 55 by wire 152, resistance 153- and wires 154 and 156. The function of resistance 153 is to prevent secondary 145 from short circuiting the battery. An impedance coil 157 is interposed in wire 156 .to choke back the flow of alternating current so that it willnot pass to the battery. The power supplied from secondary 145 to the rails is of such amplitude that magnetic fields of suificient strength to affect the magnetron tubes will be created about the rails. These magnetic fields are indicated in Fig. 2 by'the circles surrounding the rails, and it will be understood that the arrows associated with the lines of force refer to the direction of one swing of the track circuit current and that the reverse directionwould have to be indicated during the opposite swing. It will now be understood that the presence, in therails, of current from 145 will choke down the current in the train-carried charged circuit so i that it will have the intermediate value of 0.20, and therefore the circuit under control of relay 24 will remain closed.

If block 0 be unoccupied, then track relay 148 will be energized and train-control current from secondary 145 will pass to the rails of block B, with the result that if a train enters block B from block A, such train will have its magnetron tubes controlled thereby giving a clear indication. On the other hand, if block C is occupied whena train enters block 13' from A, then such train, entering block B from A, will receive'no train-control current because track relay 148 of block C will have been deenergized' by the train in block G thereby dropping armature 147 and opening the circuit from secondary 145 to rails. The efiect of this condition on the train is that a'currentvalue "of 1.00 is established in the charged circuitpassing through relay 24, and that therefore the circuit through 33 is rupturedi r i i v It will further be observed that, although the presence of a train in block C deenergizes track relay 148 and thus cuts off train-control current from the rails of block B, track relay 148 of block B will nevertheless remain energized (provided B is unocupied) by reason of current fiow from battery 158-so that a train in block A will not be controlled by a train in block C. 1 Y

If a train enters a by another train, then the train so enterlng will be subject to no train-control current. In Fig. 4 is shown a modified form of the invention by means of which a reversal of polarity of a trackcircuit current is'utilized to give different indications on the train.

This is accomplished by having'a polarized electron tube, or, to put it another way, by

placing an electron tube within the zone of influence of a magnetic field created in a conductor,-such as a rail or otherwise, and by providing a coil around said tube, whichcoil is energized'by a train-carried source. The electron tube of the magnetron type is indi cated atM and is placed on the train withinthe zone of influence of a magnetic field created in conductor or rail 1. 46 indicates a coil or winding surrounding said tube and said winding is included in a charged circuit on the train here represented by commutator G wire 34, polarizing coil-'46, filament 35' and wire 36 back to C This creates a magnetic field in coil '46, the lines of force of which are parallel to the axis of tube It is well known that one of-the operating characteristics of a magnetron tube, is that a controlling magnetic field exerts little .or no influence on the plate circuit current of the tube until a certain critical value of strength of field is attained, and that thereafter a relatively slight increase in the strength of the magnetic field will exert an influence sutficient to control the plate circuit current, the result of which is that said plate circuit current is very materially choked down in value. In Fig. 5 this operating characteristic is illustrated. In that figure, the absciss'ae represent strength of magnetic fields, and the ordinates represent different values of plate circuit current. Let abscissa EF represent: the strength of the magnetic field produced by coil 46 when energized byC such strength being somewhat less than the critical value of a cuit current in tube M. If we now add a sec-- ond magnetic field, the strength of which is represented by line FG, and this field is of the same polarity as that represented by block already occupied field suificient to control the plate c-ir- EF, thenthe resultant magnetic field isrepresented by abscissaEG; Let u's now assume that the strength of the magnetic field represented by EG is sulficient to exert a control of the plate circuit current-0t the tube such thatthe value ot said plate circuit current is choked downfrom the value represented by ordinate OH to that represented by ordinate OI. It will be evidenttherefore that it conductor 1 is devoid of current then the strength of the magnetic field of coil 46 will be represented by EF but that if current of a certain polarity flows in conductorl, the strength of themagnetic field will be represented by EG. Further that if current of reversepolarity flows in conductor 1, then the resultant magnetic field will be equal to line JK becausein that event the magnetic field created bythetrackway apparatus will be subtracted from that'represented by EF. The field represented by JK will exert no influence on the plate circuit current and the value of the latter will therefore be represented by ordinate OI-I'.

' Describing now theZtrain-carried equipmentshown in Fig. 4 more in detail, it will be seen that land 2 represent conductors, here the trafiic rails, and that 'carriedbythe train closely adjacent to said rails are. magnetron tubes -M and M; Polarizing coil 46 of tube M is connected to commutator G in the manner previously described and polarizing coil ,7

50 of tube M is connected to wires '34 and 36 by wires 38 and 39, the connection passing through filament 37 ot'tu'be M as shown in thedrawings. 'It will be seen that current inthese circuits heat filaments 35and-37 and that it is merely a: matter of convenience to include co1ls46 and 50 in sci-Les with the filaments. Obviously'coils 46fand 50could-be' energized by current in circuits-not passing through fila1nents'35 and 37. The plate circuit of tube'Mis here as follows: from cominutato rC by wire 40, to coil of relay R, wire 45,plate 48 ofM, filament 353 and .wires 36 and-43 back to C. The plate circuit for tube M is here as follows: commutator C,

wire 40, wire 44, coil ot'relay R, wire 41.,- plate52 of M, filament 37, and wires 39, 36 and 43'back to C. The traffic governing means are here represented bysignals, the

circuits for which'are as follows: from a suitable source such as the headlight. gener ator, bywires 58 and 54, neutral armature 26 of R, wire 27,ne'utral. armature 18 of R, wire 29, polarized armature 55" of R, w re 57, polarized armature 58 0 5R, wire 60, clear light 61and wires 62 and 63 back to source. The circuit for the caution light is the same as that previously-traced in connec tion with the clear signal 1 up to polarized armature155",*from which po nt with said armature: 55f in'the right hand position. the circuit-passes along wire 651to caution light 66 and then back to source by wires 62 and 63-. Thecircuit :to the danger lightis the same :as that previously described in connection-with the clear-light up to neutral arm-ature 26. which latter-will ,now be considered 7 as jbeingin itsidown POS1iElOI1,7fihB:C1I-Cll;it from thence passing to: back-contact 10-,- wire 68,-.

danger signal 69-.and :thenc-e bywires 62 and 63 back to source. Or, the danger circuit may be as previousl-ydescribed in connect on with the clear li ht u oto' neutral armature 18 of R which mustnow beconsidered as. being in its lower position, the-circuit then passing to back contact 31 and thence by wire 68 to light: :69 as before. A ain, the

"- clangercircuit may be as previously traced for the clear signal up to polarized armature 58: of R which must now be considered asbei-ngginitsleft hand position,- the circuit thence passingv by wires 32131161 68 to 69 as before. As previously indicated the source of .power for the train-carried equipment can corrveniently' be the headlight generator, and current from the latter is utilized to operate a generator G capable of delivering two I voltages.- .Specifically, wires 53 and 63 eg-:-

tend from the headlight generatorwto motor M and the latter drives commutator C which delivers a. voltage appropriate to the plate-circuit of the tubes, and also a co1nn1utator G that delivers voltage su'table for polarizing" coils 46 and 50 and forheatingthe' filaments of the tubes.

Under clear traffic conditions, current of a certain polarity flows in railsl and 2. The

magnetic field created by this rail current is of such polarity as to oppose the magnetic field created by coil; 46,]and the plate circuit current of tube M will therefore be abovea prescribedinterinediate value, iii-fact it Wlll be equal-to'the full value-of current delivered by C, which full'valuewe have arbitrarily designated by 1.00. Neutral armature 26 will therefore'bein its up position, and polarized armature will be in its left hand 1 position. The magnetic 'field created by therail current has, however, the opposite effect upon tube M, becausethe arrangement is such that the polarity of. the magnetic 'field created by the rail current, under clear traflic J conditions, is the same as that of coil 50,.

Consequently, the value of the current flowing in the plate circuit of tube'M' is choked down to the intermediate value which we have designated by 0.20, and therefore neutral armature 18 will be in its. upposition, and

polarized armature 58 will be in its righthand position. Safety signal 61 will therefore be lighted. Under caution conditions, the polarity of thecurrent in the traffic rails will be the reverse of that previously noted, and it follows therefore that the polarity of the magnetic fields created bysaid rail current will also be .reversed with. the .resultthat the plate circuit current of'tube M is choked down to the prescribed intermediate value,

and the plate circuit'current of tu'beM is allowed to flow at its full value. The effect of this will be to reverse the position of polarized' armatures 55 and 58, the former seeking the right hand position and the latter seeking theleft hand position. The neutral armatures 26 and 18 remain in the up position. Therefore caution signal 6'6'will be lighted. When rail current .is absent, as when a second train enters a block already occupied by a first train, then said secondtra-in will not be subject to the influence of rail current, and thereforecurrent of full value will flow in the plate circuits of both tubes M and M and; consequently polarized armatures' 55 and. 58: will both seek the left hand position, neutral armature 26 and 18.remaining.up,and danger signal 69 will be lighted.-

In Fig. 3 is shown'an example of trackway equipment capable of beingemployed in connection with the train equipment of Fig; .4. As there disclosed, traific rails 1 and 2 are divided intoblocks, V, X, Y and Z andthe normal direction of traffic is indicated by the arrow. 72indicate's a trackbattery connected to the rails by wires 76, 80, 73.and ;7 7 and by arniatures 7'5 and 79', :which latter are un-' der the controlof track-relay 71 of the block in advance. When no. train occupies block Y, track relay'71isenergized and armatures T9 and 75- are inthe up position againstfront. contacts 7 Sand 74.. Current of agivenpolarity will flow to rails -1 and 2 of block X; from battery .72. If block Y is occupied, then relay 71 will be deenergized-and-armatures 79 and 75 will: drop into engagement withback contacts: 83 and 82, and therefore. current of the'reverse-polarity from that pres viously assumed will be supplied to rails .1- and-20f block If block X is occupied'b-y a train, and a second trainshould enter'said block X behindthefirst one, thensaid second train will not be subjected to the influence ofv any current as the first train will have shunted the current from track battery 72. It will, .of course, be understood that. track relay 71 is energized by current of either polarity; I I

Iclaim:

y 1. Atrain control system including: a conductor extending along the line of way so as to be capable-of substantially continuously influencing,trainscarried equipment, trackway Ineansto create lines of magnetic force about said cond'uctor,a train, a charged circuitIon the train, an electron tube, included in said circuit, located within thezone of influence of said l nes of magnetic force and directly susceptible anjd substantially continuously responsivethereto to thereby vary the current flow'in said circuit, and atrafiic-gov erning translating device also included in. saidcircuit and control ledby thercurrent flow therein. 7 v

2. A train control system including: a conductor extending along the line of wayso as to be capable of substantially continuously influencing train-carried equipment and arranged in blocks, trackway means, associated with each block and controlled by traffic conditions of another block. to create lines of magnetic force about said conductor, atrain, a charged circuit on the train, an electron tube, included in said circuit, located within the zone of influence of said lines of magnetic force and'directly susceptible and substantially continuously responsive thereto to thereby varythe current flow in said circuit, and a traflic-governing translating device also included in said circuit and controlled by the current flow therein.

3. A train control system including: a conductor extending along the line of way so as to be capable of substantially continuously influencing train-carried equipment and arranged in blocks, trackway means, associated with each block and controlled by traffic conditions of another block, vto create, throughout a block, lines of magnetic force about said conductor, a tra n, a charged cir-u cuit onthe train, an-electron tube, included 1n sald circult, located within the zone of mfluence of said lines of magneticforce and continuously and directly susceptible and 30 substantially continuously responsive thereto to thereby vary the current flow in said circuit, and a trailic-governing translating device also included in said circuit and controlled by the current flow therein.

4. A train control system including: traf-v fic rails, trackway means to create lines of magnetic force about said traific rails, a train, a charged circuit onsaid train, two electron tubes, included in said circuit, located one within the zone of influence of the lines of magnetic force of one rail and the other within the zone of influence of the lines of mag nctic force of the other rail, each of said tubes being directly susceptible and responsive to the lines of magnetic force of the railiwith which it'is associated, to therebyvary the current flow in said circuit, and a trafiic-gov erning translating device also. included in said circuit and controlled by the current flow I therein;

5. A train control system including: tratlic rails arranged in blocks, trackway means, associated'with each bloclrand controlled by trafiiclconditions of another block,

to create lines of magnetic force about said trailic rails, a train, a charged'circuit on said train, two electron .tubediincluded in said circuit, located one within the zone of influence of. the lines of magnetic force of one rail and the other within the zone ofinfluence of the lines of magnetic force of the other rail, each of said tubes being directly susceptible and responsive to the lines .of magnetic force of the rail with which it is associated, to thereby -vary the current flow in said circuit, and

a traflic-governing translating device also in cluded in said circuit and controlled by the current flow therein.

"6. A train control system including:

one within the zone of influence of the lines of magnetic force of one railand the other within the zone of influence of the linesof 2 magnetic force of the other rail, each of said tubes being continuously and directly susceptible and responsive to the lines of magnetic force 'ofthe rail with which. it is associated, to therebyvary the current flow in said a circuit, and a trafiic-governing translating device also included in said c1rcu1t and controlled by the current flow therein. 7. A. train control system including:

traflic rails, trackway means to create lines of magnetic torcefabout said traflic rails, a

train, two electron tubes onthe train located one within the zone of influence of the lines 03": magnetic force of one railand the other within the zone of influence of'the lines of magnetic force of the other rail, each of said tubes being direc'tly'susceptible and responsive to the lines or magnetic force of the rail with which it is associated, and trafficgoverning means on the train controlled by the tubes. t

8. A train control system including: trafiic rails arranged in blocks, trackway means, associated with each block and controlled by traflic conditions of another block,

to create lines of magnetic force about said traflic rails, a train, two electron tubes on the train located one within the zone of influence 'ofthe lines of magnetic force of one rail and the other'withinthe zone of influence of the lines of magnetic force of the other rail, each of said tubes being directly susceptible and responsive to the lines of magnetic force of the rail with which [it is associated, and

'traflic-governing means on the train controlled by the tubes.

9. A train control system including:

traflic rails arranged in blocks, trackway means, associated with each block and controlled by traific conditions of another block, Y

to create, throughout the rails of a block, lines of magnetic force about said traiiic rails, a train, two electron tubeson the train located one within the zone of influence-of the lines of magnetic force of one railand the other within the lines ofmagnetic; force of the other rail, each of said tubes-being continuously and directly susceptible and responsive to the lines of magnetic force of the rail with whichit is associated, and traffic-governing means on the train controlledby the tubes.

g 10. A train control system including: a conductor extending along the line of Way so as to be capable of substantially continuously influencing train-carried equipment, trackway means to energize said conductor, a train, means on the train comprising: an

' electron tube in close proximity to but separated by an air gap from the conductor and directly susceptible and substantially continuously responsive to the influence of current in the conductor, a circuit including'said electron tube, and a traffic-governing translat ing device also included in said circuit but located remote from the conductor.

11. A train control system including: a trackway arranged in blocks, a track circuit for each block having a. current source, a train, a train-carried magnetically controlled electrondischarge devicelocated within the zone of influence of and continuously influenced-by'the magnetic field created by current flowing in the trackcircuit for the block through which the train is traveling, and a train-carried traflic-governing circuit controlled by the electron discharge device.

12. A train control system including: a trackway arranged in blocks, a track circuit for each block having a current source and responsive to traflic conditions of another block, a train, a train-carried magnetically controlled electron discharge device located within the zone of influence of and continuously controlled by the magnetic field created by current flowing in the track circuit'for the block through which the train is traveling, and a train-carried traffic-governing circuit controlled by the electron discharge device.

13. A train control system including: traffic rails arranged in blocks, a track circuit for each block, normally completed through the traflEic rails, having a current source and responsive to traflioconditions of another block, a train-carried magnetically controlled electron discharge device located within the zone of influence of and continuously controlled by the magnetic field created by current flowing in the tratlic rails of the block through which the train is traveling, and a train-carried traffic-governing circuit controlled by the electron discharge" device.

' 14. A train control system including: traffic rails arranged in blocks, a track circuit for each block normally completed through the trafiic rails, a source of current for said track circuit, a train, a train-carried closed circuit having a flow of direct current, a traincarried magnetically controlled electron detector, located within the zone of influence of and continuously influenced by the magnetic field created by current flowing in the tralfic rails of the block through which the train is traveling, to control'the flowof the direct current in the closed circuit, and a train-carried traffic-governing relay controlled by the direct current flowing in the closed circuit. V

'15. A train control system including: traffic rails arranged in blocks, a track circuit,

foreach block normally completed through thetraflic rails, a source of current for said track circuit, a train, atrain-carried closed circuit having a flowof direct current of a given value, a train-carried .magnetically controlled electron detector, located within the zone of influence of and continuously influenced by the magnetic field created by current flowing in' the tratfic rails of the block through which the train is traveling tolessen the value of the direct current flowing in the closed circuit, and a train-carried traffic-gov erning relay controlled by the direct current flowing in the closed circuit. Y

16. A train control system including: traffic rails divided into cuit including the rails of a block and responsive to traflic conditions of another block, a trackway source of current forsupplying said circuit with a current flow to create a magnetic field about said rails, a train, a

train-carried traflic-governing translating means, and a train-carried magnetically controlled electron discharge device located within the zone of influence of and continuously controlled by the magnetic field existing blocks, a trackway 'cirabout said rails to control said traflic-governi continuously controlled by the magnetic field existing about said rails to controlsaid tratficcovering translating means. I

18. A traincontrol system including: traffic rails divided into blocks, a trackway circuit for each block including said rails and responsive to traffic conditions in advance, a trackway source of currentfor supplying said circuit with a current flow to create a magneticfield about said rails, a train, a train-carried charged circuit having a current flow of a given value, and a traincarried magnetically controlled electron discharge device located within the zone of influence of and continuously responsive to the magnetic field about said rails to lessen the flow of current in said charged circuit to an intermediate value. I

19. A train control system including: traffic rails divided into blocks,.a track circuit for each'block inclu-dingthe rails of a block and responsive to traflic conditions of another block, a trackway source of current for supplying said circuit with a flow of current to create a magnetic field about the rails, a train-carried electron discharge device positioned within the zone of influence of said magnetic field and controlled thereby, and a train-carried traffic-governing means controlled by said electron discharge device.

20. A train control system including: traffic rails divided into blocks, a track circuit for each block including the rails of a block and responsive to traffic conditions of another block and of the block with which it is associated, a trackway source of current for supplying said track circuit with a current flow'to create a magnetic field about the rails, a train, a tram-earned electron d1scharge crevice positioned within the zone of influence of said magnetic field and controlled thereby, and a train-carried traflic-governing means controlled by said electron discharge device.

21. A train control system including: a train, two train-carried polarized relays, means acting during a given traific condition to simultaneously energize the relays, one with current of one value and the other with current of a different value, and a traincarried circuit held closed jointly by the two relays.

Signed at SWissval-e, in the county of Allegheny and State of Pennsylvania this 13th day of November, 1930.

ABBA G. WILLIAMSON. 

